From b7683335146bfe3a74d9419db92cd7a8019a9c10 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Mon, 13 Dec 2010 14:22:35 -0500
Subject: [PATCH] Disallow ligature substitutions replacing one glyph

---
 src/hb-ot-layout-gsub-private.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/hb-ot-layout-gsub-private.hh b/src/hb-ot-layout-gsub-private.hh
index 169290b5c..ae1c5f3c5 100644
--- a/src/hb-ot-layout-gsub-private.hh
+++ b/src/hb-ot-layout-gsub-private.hh
@@ -345,7 +345,7 @@ struct Ligature
     unsigned int i, j;
     unsigned int count = component.len;
     unsigned int end = MIN (c->buffer->len, c->buffer->i + c->context_length);
-    if (unlikely (c->buffer->i + count > end))
+    if (unlikely (count < 2 || c->buffer->i + count > end))
       return false;
 
     bool first_was_mark = (c->property & HB_OT_LAYOUT_GLYPH_CLASS_MARK);